A technique that increases operability in changing the rotational speed of a spindle in a power tool. The rotational speed can be changed in three levels by utilizing a planetary gear mechanism. The third gear position is located in an intermediate position in the sliding direction of the speed changing part. The first speed change position is located on one side of the third speed change position. The second speed change position is located on the other side of the third speed change position. During operation, shifting between the first and third speeds can be done without going through the second speed each time. Further, shifting between the second and third speeds can be done without going through the first speed. Therefore, speed change shifting can be facilitated.